In metal making furnaces of the prior art, sand is filled into the furnace, and particularly into a tap hole before the furnace is filled with a charge of metal, for example, sorted scrap or other metal feedstock. For example, in steel making furnaces, a tap hole is often filled with sand in incremental amounts after an operator inspects the tap hole to determine whether additional sand is required to properly fill the tap hole. The operator may use a camera or other device to visually inspect the tap hole at several different times during the sand filling cycle. Often, there will be delays as the operator waits for a clear view of the tap hole, as dust settles after an incremental fill, to see whether additional sand must be dispensed to properly fill the tap hole.
In prior art sand filling systems, the sand is often dispensed directly from a bulk storage sand reservoir often located near the furnace, for example, on a structurally reinforced roof above the furnace, or on an interior floor space of the metal making plant. In those instances where the sand must be supplied as unguided charges of sand in discrete incremental steps, and particularly in those instances where the volume of sand must be adjusted to compensate for sand dispensed into the furnace, but not into the tap hole, production time will be lost dispensing additional increments of sand to properly fill the tap hole.
In some prior art systems, such as the system of US patent publication number US 2013/0320601 published on Dec. 5, 2013 by Nucor Corp., additional production time may be lost by operating a plunger to clear metal flash and other formations which may plug or obstruct an access port, for example, a chimney hole used as an unrestricted opening to fill sand into a tap hole in a steel making furnace. The chimney hole may be cleared by a remotely controlled plunger as disclosed in the Nucor application, or in some instances, the obstructions may be cleared manually by an operator who could be exposed to risk of injury while working in close proximity to the high temperature furnace. Any obstructions are removed and sand is incrementally charged into that tap hole after the operator performs visual inspections following each sand filling step, of which there would be several incomplete filling steps, until the sand filling is properly completed. Each incremental charging step adds to the production time for the metal making process. Similar issues may arise in those systems where an operator will interrupt the sand filling cycle to manually clear obstructions from chimney holes or similar openings used to supply sand into a metal making furnace. Therefore, it would be desirable to reduce the frequency and duration of any clearing steps and to reduce the risk to operators who might otherwise be required to approach an operating furnace to clear obstructions that might interfere with sanding of the furnace or inspecting the tap hole.
Often, an unnecessarily significant amount of sand may be lost as some of the sand is dispensed, unguided, into the furnace to accumulate adjacent but outside of the tap hole. The total additional volume of used sand which is dispensed and accumulated outside of the tap hole may represent a significant expense for each production cycle, and an even greater expense over a lengthy production period. In many instances it will be desirable to reduce the consumption of sand during operation of metal making furnaces.
It would also be desirable to reduce the operating time for a metal making furnace, where possible, by reducing the amount of time needed to dispense sand into the tap hole of a metal making furnace. In some instances, it may be desirable to more accurately direct a stream of a predetermined amount of sand into the tap hole.
The present invention may be applied to sanding systems and methods of sanding metal making furnaces, for example, steel making furnaces, to ameliorate one or more of these disadvantages or one or more of the other disadvantages associated with prior art sanding systems and methods which are known by persons skilled in the prior art.